Waveform producing device

ABSTRACT

A single resistor bar having a plurality of connection points is formed by a diffused layer on a semiconduuctor substrate. A predetermined voltage is applied across the resistance layer so that the respective connection points exhibit different potentials. A decoder designates, via a reading switch circuit and successively at a predetermined time rate and order, which of the potentials to read out. Thus sequentially read-out voltages constitute a waveform of a particular tone color or an envelope of a particular shape. The decoder and the reading switch circuit may be formed by MOS transistors, and the circuits thus formed may be combined together with the resistance layer in an integrated structure on the semiconductor substrate.

United States Patent [191 Tomisawa et al.

[ 1 June 17, 1975 WAVEFORM PRODUCING DEVICE [73] Assignee: Nippon Gakki Seizo Kabushiki Kaisha, Shizuoka, Japan [22] Filed: Oct. 23, 1973 [21] Appl. No.: 408,430

[30] Foreign Application Priority Data [58] Field of Search". 340/173 R, 173 SP, 173 DR; 338/17, 22 SD 3,735,367 5/1973 Bennett 340/173 R Primary ExaminerTerre11 W. Fears Attorney, Agent, or Firm-Holman & Stern [57] ABSTRACT A single resistor bar having a plurality of connection points is formed by a diffused layer on a semiconduuctor substrate. A predetermined voltage is applied across the resistance layer so that the respective connection points exhibit different potentials. A decoder designates, via a reading switch circuit and successively at a predetermined time rate and order, which of the potentials to read out. Thus sequentially readout voltages constitute a waveform of a particular tone color or an envelope of a particular shape. The decoder and the reading switch circuit may be formed by MOS transistors, and the circuits thus formed may be combined together with the resistance layer in an integrated structure on the semiconductor substrate.

[56] References Cited UNITED STATES PATENTS 8 Claims, 29 Drawing Figures 3.721.964 3/1973 Barrett 340/173 R GND(OV) Elm-4v AMPLITUDE l g H :1'1111111:ijilillilij; 21; 2

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1. A waveform producing device which comprises, a. a resistor zone of a diffused layer formed on a semiconductor substrate and having a plurality of connection points, b. means for applying a predetermined voltage across the resistor zone so that different potentials appear at the respective connection points, and c. a reading circuit for reading the different potentials at the connection points in a predetermined order, so that a waveform having variation of amplitudes corresponding to variation of the potentials at the connection points thus read is produced.
 2. A waveform producing device as claimed in claim 1 in which said reading circuit comprises a. a read-out switching circuit having a plurality of switching transistors with input terminals connected to said connection points and with a common output terminal, and b. an addressing circuit for turning on the switching transistors in a predetermined order according to binary-coded signals to drive the switching circuit so as to produce said waveform at the common output terminal.
 3. A waveform producing device as claimed in claim 2 in which said switching transistors are MOS transistors, said addressing circuit includes a decoder formed by a plurality of MOS transistors, said switching circuit and the decoder together with said diffused resistance layer being combined in an integrated structure on said semiconductor substrate.
 4. A waveform producing device as claimed in claim 1 in which said voltage is applied through at least one resistor to the connection points on said diffused resistance layer.
 5. A waveform producing device as claimed in claim 4 in which said resistor is a diffused resistance layer formed on said semiconductor substrate.
 6. A waveform producing device as claimed in claim 4 in which a connection point connected with said resistor is shorted by another connection point.
 7. A waveform producing device as claimed in claim 4 in which connection points to which said resistor is not connected are connected to each other.
 8. A waveform producing device as claimed in claim 1 in which said voltage is applied to said diffused resistance layer through a resistor for every predetermined number of connection points and a multiple T-type attenuation circuit is formed. 